What's on my rocks
Probably quartz (http://www.pitt.edu/~cejones/GeoImages/1Minerals/1IgneousMineralz/Quartz/QuartzWhite.jpg) which is made up of silica and oxygen.
Most minerals on the surface and in soils are silica based, but if you add elements like Mg, Al or Fe (iron) they take on other colors. So the red colors on your rock indicate Fe while the clear indicate more silica.
Clear glass can be made from beach sand, which is small broken up pieces of quartz that would have weather off of your lava rock. Quartz is very resistant to breakdown at the earths surface, and that's why it ends up on the beach.